Neurofibromatosis Type 2-Schwannomatosis (NF2-Schwannomatosis) is a genetically determined disorder which affects one in 40,000 individuals worldwide. It is clinically distinct from NF1 and is ten times less common. Individuals with NF2-Schwannomatosis will not develop NF1, and those people born with NF1 will not progress to NF2-Schwannomatosis.
One of the frustrating aspects of NF2-Schwannomatosis is its variation from individual to individual. In this regard, the medical problems and the time course of NF2-Schwannomatosis may be different, even in members of the same family.
Common Features of NF2-Schwannomatosis
In general, most individuals with NF2-Schwannomatosis experience their first symptoms during the late teenage years or in their early 20s. A few people develop symptoms in childhood and some do not have problems until their 40s or 50s.
Affected individuals may develop a variety of symptoms, including:
Individuals with NF2-Schwannomatosis develop nervous system tumors that may require treatment. Since the tumors grow slowly, they may be present for many years before causing symptoms. For that reason, NF2-Schwannomatosis should be evaluated at least annually for tumors, hearing, and cataract formation. The optimal and recommended approach involves evaluation by a multidisciplinary team of specialists who can provide a diverse and expanded level of expertise on this condition.
Vestibular Schwannomas
Vestibular schwannomas are tumors that develop on the cranial nerves that carry hearing and balance signals from the ears to the brain. Almost all individuals with NF2-Schwannomatosis will develop these tumors, which are commonly seen on both sides.
This nerve contains two portions: the vestibular portion is important for balance, and the acoustic portion is responsible for hearing. For this reason, some of the earliest symptoms relate to these functions, including hearing loss, ringing in the ears (called tinnitus), and problems with balance. These tumors can be detected by magnetic resonance imaging (MRI) of the brain.
Schwannomas
People affected with NF2-Schwannomatosis can develop other nervous system tumors, called schwannomas, which may develop on other nerves in the body. The symptoms of a schwannoma will depend on the location of the tumor. For instance, schwannomas growing on nerves near the spinal cord may cause numbness or weakness in a part of the body, like the arm or the leg.
Schwannomas may also grow on small nerves in the skin, appearing as a small bump. These superficial schwannomas rarely cause neurological problems, but they may rub on clothing or be cosmetically disfiguring.
Meningiomas
The second most common tumor in NF2-Schwannomatosis is meningioma. This tumor grows from the lining around the brain, causing pressure on the brain or spinal cord. While most are benign (non-cancerous), they may cause neurologic symptoms, including headache, seizures, and weakness.
Other tumors in NF2-SWN
Less commonly, people with NF2-Schwannomatosis may develop other tumors affecting the brain or spinal cord, including ependymomas, tumors growing on the lining of the spinal cord and brain. These tumors can cause neurological symptoms, depending on their location.
Some individuals with NF2-Schwannomatosis may develop a special type of cataract, known as a juvenile posterior sublenticular opacity, or experience other problems with the eyes.
Since cataracts cause clouding of the lens and are likely to impair vision if not removed, it is important for all individuals with NF2-Schwannomatosis to have a detailed eye exam by a specialist familiar with NF2-Schwannomatosis.